Plymouth, MN Environmental Rules: Stormwater Management (2026)
Key Facts
- MS4 discharge rule
- Only storm water may enter the system
- Illicit connections
- Sewage lines into storm drains banned
- Salt storage
- Must be covered/indoors, impervious surface
- Spill notice
- Next business day, written confirm in 5 days
- Governing sections
- Plymouth City Code §§ 725.14-725.17
Summary
In the City of Plymouth, Minnesota, City Code Sections 725.14 through 725.17 ban dumping anything but storm water into the City's storm drain system, the MS4, and separately prohibit illicit connections such as sewage lines tied into storm sewers. Violations fall under Chapter XX enforcement, and the City may enter private property without prior notice to abate a discharge that endangers public health or safety.
725.14. - Prohibition of Illegal Discharges. No person shall throw, drain, or otherwise discharge, cause, or allow others under its control to throw, drain, or otherwise discharge into the MS4 any pollutants or waters containing any pollutants, other than storm water. The commencement, conduct or continuance of any illegal discharge to the storm drain system is prohibited except as described as follows: ... 725.15. - Prohibition of Illicit Connections. The construction, use, maintenance or continued existence of illicit connections to the storm drain system is prohibited. ... 725.17. - Enforcement. It shall be unlawful for any person to violate any provision or fail to comply with any of the requirements of this ordinance. Any person who has violated or continues to violate the provisions of this ordinance may be subject to the enforcement actions outlined in Chapter XX.
Full Breakdown
17. 14 bars any person from throwing, draining or otherwise discharging pollutants, other than storm water itself, into the City's Municipal Separate Storm Sewer System (MS4), which includes streets, catch basins, curbs, gutters, ditches and storm drains the City owns and operates. The Code exempts a specific list of flows from that prohibition: water line flushing, landscape irrigation, uncontaminated ground water, foundation and footing drains, air conditioning condensation, individual residential car washing, and dechlorinated swimming pool discharges made under Section 740, among others, plus firefighting flows and any discharge already covered by an NPDES permit issued under the federal Clean Water Act.
15 separately prohibits illicit connections, including any line carrying sewage into the MS4, whether the connection predates this ordinance or not, and requires the property owner to locate and disconnect an undocumented drain at their own cost once the City gives written notice. 16 requires anyone responsible for a spill that may reach the storm drain system to contain and clean it up immediately, notify emergency responders for hazardous releases, and notify the City by the next business day for non-hazardous releases, confirmed in writing within five days.
5 requires commercial, institutional and industrial salt storage areas to be covered or indoors and set on an impervious surface. 17, any violation is subject to the enforcement remedies in Chapter XX, and where a discharge is an immediate danger to public health or safety, the City may enter the property without prior notice to abate it at the owner's expense.
Violations & Fines
Violating the discharge or illicit-connection prohibition is enforceable under Chapter XX's general penalty, which makes a Code violation a misdemeanor punishable by up to $700.00 and 90 days in jail, with each day of a continuing violation a separate offense. The City can also enter the property without notice to abate an immediate health or safety danger and bill the owner for the cost.
Frequently Asked Questions
Can I discharge my sump pump or pool water into the storm drain?
What counts as an illicit connection under Plymouth's stormwater rules?
Do I have to report a chemical spill that might reach a storm drain?
Can the City enter my property over a stormwater violation?
Sources & Official References
Other rules in Plymouth
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Stormwater Management in Nearby Cities
How other cities in Hennepin County handle stormwater management.